The expansion of Heathrow airport has already been secretly approved by Whitehall transport chiefs, it was reported today.
Senior government figures have already sanctioned a third runway even though thousands of objections are still being sifted through as part of the public consultation, according to the Times newspaper.
Transport secretary Ruth Kelly is preparing to make an announcement as early as November, it is claimed.
The news has been met with anger by anti-expansion campaigners who have fought the proposals from the outset.
John Stewart, chairman of HACAN ClearSkies, said: "If it is true that the government has taken a decision before fully assessing the 70,000 consultation responses then it's clearly open to a legal challenge. We'll be keeping a close eye on this, and it's very likely we'll be consulting with our lawyers."
The third runway, which could cost anywhere between s7billion and s13billion, would boost Heathrow capacity from 480,000 flights a year to 702,000.
A spokesperson for the Department of Transport said: "It is wrong to say that we have already decided that a 3rd runway at Heathrow should go-ahead. As stated in the 2003 Air Transport White Paper the Government supports a third runway in principle, but we have always said that expansion will only go ahead of strict environmental limits can be met. We expect to make a final policy decision on this by the end of the year.”